US Congress Partisanship Animation

What is this?

This is the data, R script, and documentation necessary to make an animation of partisanship in the US Congress, with parallel violin plots of the House and Senate across Congresses 1 to 113 broken down by party. This is merely a data visualisation of Poole and Rosenthal’s DW-NOMINATE work, and not an analysis of raw data.

Where does this start?

All credit for data goes to Poole and Rosenthal, and their excellent work on DW-NOMINATE scores. Data was obtained from their http://www.voteview.com, with relevant downloads copied here. VoteView.com seems to be somewhat in flux, but further documentation about the data should still be available there without too much searching.

The script uses the 1st dimension coordinate, which is, according to the authors, the only one relevant after the Civil War. If you’re particularly interested in the data from early Congresses, it would make a lot of sense to rebuild the script to account for the second dimension and rebuild the party decoder to account for early political parties.

What does this do?

The operant file is the R script “partisansihp.R”, which imports the included data, modifies it as necessary, makes the plots in a new folder called “PartisanshipAnimation”, and then calls ImageMagick to compile the plots into an animated .gif file, which is saved in the same new file.

What are the results?

This .gif of partisanship in the US Congress: partisanship.gif

The output is named “partisanship.gif”, and is in the “PartisanshipAnimation” file, pre-compiled here. Also in that file is a smaller version of the animation, dithered with unnecessary colors removed via online tools at http://ezgif.com/optimize. “giphy.txt” includes links for an uploaded copy of the .gif on giphy.com.

What do I need to run the script myself?

R, to start (http://www.r-project.org/). To run the script, you’ll need the following packages (all available from CRAN):

  • xlsx
  • foreign
  • ggplot2
  • dependencies of those packages (usually automatically installed).

You’ll also need ImageMagick to compile the animated .gif. It is available free at http://www.imagemagick.org, and can be installed via MacPorts or Homebrew on OS X. You only need a command-line install, not a GUI version.

The script uses Linotype’s Trade Gothic Bold No. 2, available for a fee at http://www.fonts.com/font/linotype/trade-gothic/bold-2. You are also welcome to change the relevant code on line 71 of partisanship.R to whatever font you like.

Notes on the script

As any regular R user will quickly see, the R script is assembled with a couple major functions and a good bit of other code more akin to usage typical of interactive use of R. Given the dependencies, the script is written to be platform-independent (you shouldn’t need to update paths or anything). At some point in the future I may rewrite it in a more completely functional paradigm, but I think it’s pretty easy to see what’s happening as-is, despite the mixed paradigms.